The body believed to be that of 18-year-old Jared Brimhall was discovered Sunday washed onto a grassy bank about a half mile from where he and his girlfriend had entered the west fork of the San Jacinto River for a swim after some torrential rains four days earlier.

Brimhall had been scheduled to graduate Saturday from Conroe High School, and he also leaves behind a 2-month-old son, Brayden, his family said.

Brimhall's mother, Jennifer, thanked her friends on Facebook for their support and told how she'd prayed for the Class of 2014 to be able to enjoy their celebration for all the hard work they had done "as my son would have wanted."

The floodwaters on Sunday started to recede but the river remained treacherous when searchers spotted the body, said Precinct 4 Montgomery County Constable Capt. Mark Seals, who was riding in an inflatable boat designed for swift water and followed by two justices of the peace in an airboat. "We were being very meticulous, trying to look in areas where we thought the currents would take a body."

About 8 a.m., they spotted a body lying in a grassy area covered with about two feet of water, Seals said.

The ex-girlfriend and mother of Brimhall's child, Heather Hoefling, could not be reached for comment. But high school sophomore and former cheerleader posted this note on Instagram accompanied by a photo of Brimhall holding his infant son: "I love you Jared. I hope you find your way home. Brayden needs you more than anything. I've been praying that you are OK, and everything will be alright, this is so hard to take in. It's like I woke up and it was a dream. But it wasn't."

According to Terrence Morrison Jr., a fisherman who witnessed the teen disappear into the river, Brimhall panicked and started fighting the swirling waters, which had strong undercurrents that can suck someone down to the bottom.

Morrison said his current girlfriend, 19-year-old Katherine Warman, appeared to be the more confident swimmer, who flipped onto her back, swimming with the currents. She then maneuvered close enough to Brimhall to wrap her arms around him and try to pull him to safety, until his flailing arms caused him to break free, Morrison said. The teen sunk soon after into the dark waters and never resurfaced. His girlfriend managed to make it ashore, screaming for help, Morrison said.